Issue #22885: Fixed arbitrary code execution vulnerability in the dbm.dumb

module.  Original patch by Claudiu Popa.

2 files changed, 11 insertions, 1 deletions

diff --git a/Lib/dbm/dumb.py b/Lib/dbm/dumb.py
index 8f48aad..a9ead68 100644
--- a/Lib/dbm/dumb.py
+++ b/Lib/dbm/dumb.py
@@ -21,6 +21,7 @@ is read when the database is opened, and some updates rewrite the whole index)
 
 """
 
+import ast as _ast
 import io as _io
 import os as _os
 import collections
@@ -85,7 +86,7 @@ class _Database(collections.MutableMapping):
             with f:
                 for line in f:
                     line = line.rstrip()
-                    key, pos_and_siz_pair = eval(line)
+                    key, pos_and_siz_pair = _ast.literal_eval(line)
                     key = key.encode('Latin-1')
                     self._index[key] = pos_and_siz_pair
 
diff --git a/Lib/test/test_dbm_dumb.py b/Lib/test/test_dbm_dumb.py
index 29f48a3..dc88ca6 100644
--- a/Lib/test/test_dbm_dumb.py
+++ b/Lib/test/test_dbm_dumb.py
@@ -217,6 +217,15 @@ class DumbDBMTestCase(unittest.TestCase):
             self.assertEqual(str(cm.exception),
                              "DBM object has already been closed")
 
+    def test_eval(self):
+        with open(_fname + '.dir', 'w') as stream:
+            stream.write("str(print('Hacked!')), 0\n")
+        with support.captured_stdout() as stdout:
+            with self.assertRaises(ValueError):
+                with dumbdbm.open(_fname) as f:
+                    pass
+            self.assertEqual(stdout.getvalue(), '')
+
     def tearDown(self):
         _delete_files()